The Intensity Vector Autonomous Recorder (IVAR) simultaneously measures acoustic particle velocity and pressure. IVAR was deployed during the 2017 Seabed Characterization Experiment (SBCEX) with the primary objective to study sound propagation in fine-grained, muddy sediments. In this study a Bayesian inversion framework is applied to ship underwater noise recorded by IVAR. The data are relative phase of pressure and vertical particle velocity, a quantity that is independent of the ship noise source spectrum. Inversion estimates for the sediment layer and underlying basement properties are in agreement with other reports from SBCEX.
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http://dx.doi.org/10.1121/10.0001089 | DOI Listing |
J Acoust Soc Am
January 2025
Center for Acoustics Research and Education, University of New Hampshire, Durham, New Hampshire 03823, USA.
Fishes and aquatic invertebrates utilize acoustic particle motion for hearing, and some additionally detect sound pressure. Yet, few underwater soundscapes studies report particle motion, which is often assumed to scale predictably with pressure in offshore habitats. This relationship does not always exist for low frequencies or near reflective boundaries.
View Article and Find Full Text PDFJ Acoust Soc Am
January 2025
National Key Laboratory of Underwater Acoustic Technology, Harbin Engineering University, Harbin 150001, China.
With the vigorous development of maritime trade, the frequency band from 100 to 1500 Hz of shallow-sea ambient noise is not only affected by surface wind-induced noise but also the contribution of ship noise. Shallow-sea ambient noise can be described by a linear combination of surface wind-induced noise sources and ship noise sources. By using the correspondence between the real part of the vertical coherence and vertical energy flux, this work establishes a combined noise source model based on vertical coherence.
View Article and Find Full Text PDFSci Rep
January 2025
Naval University of Engineering, Wuhan, Hubei, China.
Shafting alignment is crucial for marine propulsion systems and may affect the safety and stability of ship operations. Air spring vibration isolation systems (ASVISs) for marine shafting can help control the shafting alignment state by actively adjusting air spring pressures while effectively reducing the mechanical noise. However, how to accurately control the alignment state of marine shafting with air spring vibration isolation system remains a challenge.
View Article and Find Full Text PDFJASA Express Lett
January 2025
College of Information and Communication Engineering, Harbin Engineering University, Harbin, 150006, China.
A modified adaptive Kalman filter (AKF) algorithm is proposed to make underwater multi-target tracking with uncertain measurement noise reliable. By utilizing the proposed AKF algorithm with three core points, including an adaptive fading factor, measurement noise covariance adjustment, and an adaptive weighting factor, the unknown measurement noise and state vector can be estimated with good accuracy and robustness. The practical trial data verify this algorithm, and it has proven superior to all traditional algorithms in this Letter based on the results that it reduces the estimated position RMSEs by at least 10.
View Article and Find Full Text PDFSci Rep
December 2024
National University of Defense Technology, Changsha, Hunan, China.
In-band full-duplex communication has the potential to double the wireless channel capacity. However, how to efficiently transform the full-duplex gain at the physical layer into network throughput improvement is still a challenge, especially in dynamic communication environments. This paper presents a reinforcement learning-based full-duplex (RLFD) medium access control (MAC) protocol for wireless local-area networks (WLANs) with full-duplex access points.
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